Forest Snapshot March 2025

Important Dates

Save the date! The PA Timber Show will be held at the Russell E. Larson Agricultural Research Center on June 6th and 7th.

Forest Health

Hemlock Woolly Adelgid Winter Mortality

This winter's weather produced an impactful amount of Hemlock Woolly Adelgid mortality in the overwintering (sistens) generation. Percent mortality ranged from 83% to 100%, with an average of 95%. Seven of ten samples so far had 95% mortality or greater, which is enough to actually reduce the HWA population in those sites. Surveys are ongoing. If we experience two winter seasons in a row with this level of HWA mortality, the overall statewide population may be reduced enough to see improvements in hemlock tree health, a much-needed (but temporary) respite.

For more information, see Aerial Applicators Licensed to Spray in PA (PDF). This list includes licensed UAV applicators in addition to manned aircraft applicators. Contracts with applicators can be with an individual landowner, a group of landowners, or homeowners together, which requires more planning but can be a way to secure services by providing enough acres to effectively spray; or set up with an applicator through your Consulting Forester. 

For aerial spraying, foliar active ingredients Btk (Bacillus thuringiensis subsp kurstaki) or tebufenozide are recommended.  For individual trees, systemic treatments or foliar UAV applications are viable and effective. Several options are available for systemic treatments, including soil injection of acephate or trunk injection of emamectin benzoate or abamectin. Sticky bands and burlap "tree skirts" are much cheaper and use no chemicals, but must be checked daily and will likely not prevent some defoliation from happening, especially with high spongy moth populations.  There are other possibilities, and the best recommendations are usually case-by-case. Contact your local service forester, Extension forester, or Forest Health staff member for additional information.

Native Species

Pennsylvania forests are starting to wake up as we move into spring. Patches of eastern redbuds (Cercis canadensis) will bloom, dotting hillsides with their pink flowers. Eastern redbud is a member of the Fabaceae or legume family with flowers resembling those of garden peas. Rather than blooming at the ends of their branches, eastern redbud will develop flowers along their stems and trunks, a phenomenon called cauliflory. Later in the season, the flowers will give way to brown bean pods. Eastern redbud is an excellent native Pennsylvania tree that can be incorporated into landscaping for added seasonal color. Keep an eye on the mountains this spring for the pink-purple swaths of eastern redbud in bloom.

Wildlife and Insects

Come April, bats wake from hibernation and are busy feeding to replenish and prepare for the upcoming mating season. Soon, porcupine pups are born in their rock or tree dens after a gestation period of 205–217 days. When born, porcupines are already able to open their eyes and have fur and soft quills. They climb trees within a matter of days.

Start listening for mountain chorus frogs, pickerel frogs, and green frogs calling. In May, Fowler's toads begin to mate. Their call is a nasal "wraaah," relatively high-pitched in tone. Toads lay their eggs in long strands, whereas frog and salamander eggs are laid in globular clusters. Frog and salamander larvae hatched from eggs laid in early spring are close to metamorphosis.